1787, from Scottish, apparently an alteration of M.E. glenten "gleam, flash, glisten," from Scand. (cf. Norw. gletta "to look," dial. Swed. glinta "to shine"), from P.Gmc. *glent-, from PIE *ghlei- "to shine, glitter, glow, be warm" (see gleam
). Introduced into Eng. by Burns.